Matthew 16:1-3

Then the Pharisees and Sadducees came, and testing Him asked that He would show them a sign from heaven. He answered and said to them, “When it is evening you say, ‘It will be fair weather, for the sky is red’; and in the morning, ‘It will be foul weather today, for the sky is red and threatening.’ Hypocrites! You know how to discern the face of the sky, but you cannot discern the signs of the times.